Method of producing forming screen



May 15, 1962 R. 'F. REIFERS METHOD 0F PRODUCING FORMING SCREEN 3 Sheets-Sheet 1 Filed July 17, 1959 INVENTOR {Ric/Laid gaff/1S KL, @JFtoccs FIG.

ATTORNEY May 15, 19 2 R. F. REEFERS 3,034,212

METHOD OF PRODUCING FORMING SGREEN Filed July 17, 1959 5 Sheets-Sheet 3 FIG. 5

INVENTOR zzcm gaapm K A Q L. LL) EZC K. S

ATTORNEY ware Filed July 17, 1959, Ser. No. 827,943 14 Claims. (Cl. 29--553) The present invention relates to a method of producing forming screen, and more particularly to a method of producing forming screen wherein metallic cloth is provided with corrugations.

Articles of molded pulp are conveniently produced on forming dies, these being in the proper shape and made of a heavy metal, such as brass. This die is provided with a great number of small holes extending from one surface thereof to the other. The die is immersed into a slurry of pulp fibers and water, and has suction applied to one surface thereof to draw the water through the die. A

. forming screen that extends over the forming face of the die collects the pulp fibers and prevents them from passing through the small holes. After a period of time, a thickness of pulp fibers is built up on the forming screen, and the die is removed from the slurry and the article is then removed from the die.

While the provision of forming screen for a relatively simple article, such .as a pieplate, does not present any great difficulty, the workers in the art have heretofore provided forming screens of many parts in the cases of more complex articles, such as egg trays and egg cartons. These articles are characterized by many upstanding posts and depressed cells, and in some cases it has been the practice to provide an individual piece of forming screen for each one or two of the cells and posts.

The making of the individual forming screen parts for use on a molding die for a complex article has been found to be both tedious and expensive, as is the fitting of the small pieces of forming screen together on the forming die in proper relationship to the forming die and to each other.

Thus, it will be understood that in the prior art the production of relatively complex molded pulp articles could only be accomplished at a relatively higher price than simpler articles, due in great measure to the. cost of manufacturing the multi part forming screens and in mounting these parts onto the forming die.

An object of the present invention is to provide a method of producing a forming screen for .a molded pulp forming die of highly complex shape.

Another object of the present invention is the provision of a method for producing a single forming screen which may be used for a molded pulp forming die of highly irregular shape.

Still another object of the present invention is to provide a method of producing screening that may be readily formed, in a single'piece, into a forming screen of complex configuration.

A further object of the present invention is the provision of a method of producing screening that is capable of being formed into highly irregular and complex configurations without tearing or piecing.

A still further object of the present invention is to provide a method for producing forming screen for molded pulp forming dies that will bemore economical than previously used methods, in order to reduce the cost of complex molded pulp articles.

Other objects and the nature and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view showing a first step in ice the method of the present invention, wherein metallic cloth is being corrugated.

FIG. 2 is a view similar to FIG. 1, and showing a second step in accordance with the present invention wherein the cloth of FIG. 1 is being corrugated at right angles to the step of FIG. 1. p

FIG. 3 is a cross-sectional View of a piece of metallic cloth after it has passed through the steps shown in FIGS. 1 and 2.

FIG. 4 illustrates diagrammatically further steps in the preparation of a forming screen in accordance with the present invention.

FIG. 5 is a perspective view of a forming screen of a highly complex configuration that has been made in accordance with the present invention.

Referring now to the drawings, wherein like reference characters are used for like or corresponding parts throughout the several views, there is shown in FIG. 1 a pair of crimping rollers 11 and 12, which are carried by a framework, generally denoted 13. The crimping rollers 11 and 12 have transversely extending crimp producing surfaces .14 thereon, and one or both of the rollers 11 and 12 may be rotated, as by crank 16 The axle 17 of upper crimping roller 11 is carried in a hearing that may be adjusted vertically by means of the adjusting screw 18, in known fashion. Thus, the turn- 1 ing of the adjusting screw 18 will serve, in known the nip of crimping rollers 11 and 12, and transversely of the surfaces 14 thereof. There may also be seen, in FIG. wires 21 which extend in an undulating fashion transversely of the wires 21 The wires 21 correspond to the woof threads of conventional cloth and the wires Ztl correspond to the warp threads in a-conventional cloth.

As may be seen from the cloth C extending to the right of the crimping rollers 11 and 12 in FIG. 1, these crimping rollers have produced in the cloth C a series of corrugations extending transversely of the straight wires 26.

After the cloth C has passed through the crimping rollers 11 and 1 2 as shown in FIG. 1, the rollers are slightly separated by means of the adjusting screw 18. In practice, it has been found that when the Wire cloth C is of Phosphor bronze having a mesh of 50 x 41 and a thickness of .023 inch, best results are obtained when the rolls are backed off by .020 inch. Once the rolls are separated, the piece of Wire cloth 1C is passed through the nip of the crimping rollers 11 and 12 with the straight wire 20 extending generally perpendicularly to the direction of travel. This may be seen in FIG. 2, wherein the cloth C may be seen to have single corrugations at the left of the crimping rollers 11 and 12, these single corrugations corresponding to those at the right of the rollers 11 and 12 in FIG. 1, and the cloth C having double corrugations to the night of the crimping rollers 11 and 12 in FIG. 2.

FIG. 3 is across-seotional view of the wire cloth C after it has been treated as above described in order to provide it with the double corrugations. FIG. 3 is taken on the line 3A, 3B of FIG. 2, and it will be understood that the part 3A thereof shows the appearance of the cross-section of the double corrugated cloth C which is perpendicular to the straight wires 20 and that the part marked 38 of FIG.-3 is a cross-sectional view taken parallel to the straight wire 20.- It Will be understood,

of course, that the reference to straight wires 2d is only an indication ofthe condition" of these particular wires before any corrugation hadbeen imparted to the Inetalliccloth C and that in fact -afterthe double corru-;

gations have been'imparted thereto; these straight wires 20 are not in fact straight. in the section 3A of FIG. 3, the metallic clot-h C may be seen to have a generally sinusoidal character, and is relatively flattened. On' the articles may be accomplished with a substantial reduction in cost and time, and thus thecost of the finished molded pulp articles may also be reduced.

other hand, in thecrosssection designated 33 the depth 7 V of the cloth is relatively greater.

The metallic cloth C, as it is in the form shown in FIG. 3, is adaptable to being used with a pulp forming die, as discussed herein above. It may be additionally treated as described below. I

Referring now to FIG, 4, there is show an oven 39,

' or. equivalent heating apparatus. 'The metallic clothC,

as shown in FIG. 3, is first placed'into the heating chamber 30. Preferably it is heated at a temperature of 1000 F. for a period of approximately two minutes. 'After thus being heated, the metallic cloth C is allowed to cool in still air at room temperature. Following the cooling, of the cloth C, it is placed between the mating members 3-1 and 32 of a Wire forming die 33. Such dies It will be obvious to those skilled in the art that various changes may be made'without departing from the spirit of the invention and therefore the invention is not limited to What is shown in'the'drawings and described in the specification but only as indicated in the appended 7 ticle to be manufactured.

2. The method of preparing a metallic'cloth screen for a pulp forming die as set forth in claim 1, wherein the step of forming said cloth in the corrugated area is carried out by stretching the corrugations over a die corresponding nto the shape of the molded pulp article to be manufactored; r

are-well known in the art, and are carried in a suitable press, usually hydraulic. As will be understood, the wire forming die 33 is shaped to conform to the pulp forming die on which the metallic cloth C will be subsequently placed, and of course is also of the shape of the molded pulp article to be produced. Once the metallic cloth C is placed between the mating members 31 and 32 of die 33,'the aforementioned press is actuated so that it applies a force of one ton and stretches the corrugations of the corrugated cloth C as shown in FIG. 4.

The metallic cloth C is only partially formed after this initial pressing step, and thereafter, it is again placed in order to register the partially formed metallic cloth with:

the configuration of the mating dies 31 and 32'. The press is then actuated to produce a force of twenty tons, and there thus results the desired forming screen.

While the heating and cooling of the cloth C may be elfected' as hereinabove described, these steps are not necessary and in some instances may be omitted, depending upon the character of cloth C.

An example of a complex article that may be made with a single forming screen is shown in FIG. 5, wherein cells, sixteen upstanding posts and a peripheral flange along the four sides thereof. Thus, the corresponding screen 8 may be seen to have the cells 35 andthe upstanding posts 36, as Well as the surrounding flange '37.

There hasbeen provided amethod of producing screening which may be made into forming screens with a pulp formingdie. This screening maybe formed into a highly complex forming screen of a unitary piece. of material, thus avoiding all the draw-backs of multipart forming screens. There has also been provided a method for producing forming screens in which such screens of highly complex and irregular configuration may be produced froma single sheet of metallic cloth. With-the utilization of the metallic cloth in accordance with the present invention, the problems inherent'in both piecing together individual partsof the forming screen and in the initial production of such formingscrecns, are eliminated. As

3. The method of preparing a metallic cloth screen for a pulp forming die as set forth in claim 2, whereinafter the cloth is corrugated in both-directions and before it is stretched, the double corrugated cloth is heated and then the double corrugated cloth is cooled? 4. The method of preparing a metallic cloth screen for a pulp forming die as set forth in claim 3, wherein after the stretching step the stretched cloth is heated and then cooled.

5. The method of preparing a metallic screen for a pulp forming die as set forth in claim 1, wherein the step of corrugating the cloth in the first direction is carried out by passing said cloth through mating crimping rollers having transversely extending crimping surfaces with the center-to-center distance of said rollers spaced a predetermined amount, and the step of corrugating said cloth in the second direction is carried out by passing said cloth through mating crimping rollers having transversely extending crimping surfaces withjthe'center-to-center distance of said rollers spaced more thansaid predetermined amount.

piece of the metallic cloth through mating crimping rollers,

thereafter passing the said piece of metallic cloth through said crimpingrrollers in a direction perpendicular to the first pass, whereby to produce a double corrugated piece of metallic cloth, heating said double-corrugated piece of metallic cloth, cooling said cloth, partially forming said metallic cloth in a wire forming die to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to he manufactured, repeating said heating and. cooling steps, and completely forming said metallic cloth in said wire forming die. r i

7. The method of preparing metallic cloth for use as screening on a pulp forming die comprising passing, a piece of the metallic cloth through mating crimping rollers with the straight wires parallel to the direction of travel,

thereafter passing the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel, whereby to produce a double corrugated piece of metallic cloth, heating said: doublecorrugated piece-of metallic cloth, cooling said cloth, partially forming said metallic cloth in a wire forming die to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to be manufactured, repeating said heating and cooling steps, and completely forming said metallic cloth in said wire forming die.

8. The method of preparing metalliccloth for use as metallic cloth for use as screening on a pulp forming die comprising passing a piece of the metallic cloth through mating crimping rollers with the straight wires parallel to the direction of travel, thereafter slightly increasing the center to center distance of said crimping rollers and passing the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel,

whereby to produce a double corrugated piece of metallic cloth, heating said double-corrugated piece of metallic cloth, cooling said cloth, partially forming said metallic cloth in a wire forming die to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to be manufactured, repeating said heating and cooling steps, and completely forming said metallic cloth in said wire forming die.

9. The method of preparing metallic cloth for use as screening on a pulp forming die comprising passing a piece of the metallic cloth through mating crimping rollers 'having transversely extending crimp-producing surfaces with the straight wires parallel to the direction of travel and transversely of said surfaces, thereafter passing the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel, whereby to produce a double corrugated piece of metallic cloth, heating said double-corrugated piece of metallic cloth, cooling said cloth, partially forming said metallic cloth in a wire forming die to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the-molded pulp article to be m anufactured, repeating said heating and cooling steps, and completely forming said metallic cloth in said wire forming die.

10. The method of preparing metallic cloth for use as screening on a pulp forming die comprising passing a piece of the metallic cloth through mating crimping rollers having transversely extending crimp-producing surfaces with the straight wires parallel to the direction of travel and transversely of said surfaces, thereafter slightly increasing the center to center distance of said crimping rollers and passing the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel, whereby to produce a double corrugated piece of metallic cloth, heating said double- '6 screening on a pulp forming :die comprising passing a piece of the metallic cloth through mating crimping rollers having transversely extending crimp-producing surfaces with the straight wires parallel to the direction of travel and transversely of said surfaces, thereafter slightly increasing the center to center distance of said crimping rollers and passing the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel, whereby to produce a double corrugated piece of metallic cloth, heating said doublecorr-ugated piece of metallic cloth, cooling said cloth in still air at room temperature, forming said metallic cloth in a wire forming die under a force of one ton to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to be manufactured, repeating said heating and cooling steps, and forming said metallic cloth in said wire forming die under a force of twenty tons.

13. The method of preparing metallic cloth for use as screening on a pulp forming die comprising passing a piece of the metallic cloth through mating crimping rollers having transversely extending crimp-producing surfaces with the straight wires parallel to the direction of travel and transversely of said surfaces, thereafter passing'the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel, whereby to produce a double corrugated piece of metallic cloth, heating said double-corrugated piece of metallic cloth for two minutes at a temperature of 1000 F., cooling said cloth in still air at room temperature,

forming said metallic cloth in a wire forming die under corrugated piece of metallic cloth, cooling said cloth, parcooling steps, and completely forming said metallic cloth in said wire forming die.

11. The method of preparing metallic cloth for use as screening on a pulp forming die comprising passing a piece of the metallic cloth through mating crimping rollers having transversely extending crimp-producing surfaces with the straight wires parallel to the direction of travel and transversely of said surfaces, thereafter slightly increasing the center to center distance of said-crimping rollers and passing the said piece of metallic cloth through said crimping rollers with the straight wires perpendicular to the direction of travel, whereby to produce a double corrugated piece of metallic cloth, heating said doublecorrugated piece of metallic cloth, cooling said cloth, forming said metallic cloth in a wire forming die under a force of one ton to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to be manufactured, repeating said heating and cooling steps, and forming said metallic cloth in said wire forming die under a force of twenty tons.

12. The method of preparing metallic cloth for use as a force of one ton to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to be manufactured, repeating said heating and coolingsteps, and forming said metallic cloth in said wire forming die under a force of twenty tons.

14. The method of preparing metallic cloth for use as screening on a pulp forming die comprising passing a at room temperature, forming said metallic cloth in a wire forming die under a force of one ton to make a formed screen for the pulp forming die wherein said screen corresponds in shape to the molded pulp article to bemanu factured, repeating said heating and cooling steps, and forming said metallic cloth in said wire forming die under a force of twenty tons.

References Cited in the file of this patent UNITED STATES PATENTS 662,567 Von Lipowsko et a1. Nov. 27, 1900 969,460 Chartener Sept. 6, 1910 1,589,798 Ewers June 22, 1926 1,942,451 Reynolds Ian. 9, 1934 2,361,039 Langel Oct. 24, 1944 2,798,515 York July 9, 1957 2,867,559 May Jan. 6, 1959 FOREIGN PATENTS 637,759 Great Britain May 24, 1950 

